Historical clue formulations

• Dreaded time for many — 2024-06-22
• Back-to-school time — 2020-01-26
• With 26-Across, #1 hit for the Mamas & the Papas — 2013-10-08
• When repeated, a Mamas and the Papas hit — 1998-05-28
• Starting time? — 1996-04-20